It has been previously proposed, in Criswell et al. U.S. Pat. No. 4,862,549 issued Sep. 5, 1989, to provide a device for the preparation of pipe for soldering or brazing.
That device consists of an outer annular wire brush that is secured within a holder, and, a tubular wire brush that also is secured within the holder coaxially within the annular wire brush.
While this device initially performs admirably for its intended purpose, that device is subject to rapid wear and deterioration of the respective wire brushes, which both must be used simultaneously when preparing a pipe end in readiness for soldering or brazing.
Pipe soldering or brazing operations require either the removal of oxides from the exterior of the pipe end, or, the removal of oxides from the interior of the pipe end, there being no requirement to remove oxides from both the exterior and the interior of the pipe end at the same time. A dual cleaning operation, therefore, imposes unnecessary wear on the wire brush that is being employed for cleaning that surface of the pipe end that is not to be soldered or brazed, and, additionally involves wasted energy and unnecessary wear on the power tool employed for rotating the device.
This deficiency is recognized by Miller in U.S. Pat. 5,307,534 issued May 3, 1994.
Miller proposes a hand-held power tool having a driven shaft extending there through, and which terminates at respective ends of the power tool in collets to be employed for holding and driving either an annular wire brush to be employed for cleaning the exterior of a pipe end, or, a tubular wire brush to be used for cleaning the interior of a pipe end.
While Miller overcomes the disadvantage in Criswell of imposing unnecessary wear on the wire brushes, which can be employed singly instead of in tandem, Miller requires a specialized hand tool, which possibly is not readily available at the work site. In contrast, a single ended electrical drill commonly is available at the work site, or readily can be obtained by a workman.
The purchase of the Miller dual ended specialized power tool, represents a duplication of expense in the event that an electrical drill already is available to the workmen.